Ever since automobiles were invented, there has been a need for a more energy efficient vehicle. A solution satisfying urban and suburban family transportation needs in a safe and fuel-efficient manner is desired by many for longer and more affordable commutes. In the past few decades, many scientific studies let to the belief that the increased used of automobiles worldwide is contributing to a global climate change phenomenon known as global warming, which is threatening the existence of many biological species and the current way of life of the populations in many countries. It is further believed that substituting fossil fuel uses with renewable or otherwise less polluting energy sources may result less drastic global warming effect. To further complicate the issue, the general population, substantially more so in the United States, tends to prefer larger vehicles. The demand for larger vehicles is satisfied essentially by truck-based vehicle platforms converted into passenger vehicles officially classified as light trucks. Truck platforms (or body-over-frame designs) tend to be heavy compared to regular passenger vehicles. And, the heavier the vehicle, the more energy is required to propel it over a given distance. The sharp increase in fuel consumption by light trucks collectively has been blamed for air pollution in major cities.
Obviously, there are many conventional fossil-fuel driven passenger cars (automobiles), light trucks and crossover vehicles. Vehicles are generally classified based on their sizes, weights and payload capacities. Larger light trucks, including Sports Utility Vehicles (SUV) and pickup trucks are often used as passenger vehicles and offer great versatility in terms of passenger and cargo carrying capacities. Crossover vehicles are defined as a car based platform with a light-truck appearance. Some of these vehicles are designed or retrofitted with a hybrid electric drivetrain to improve fuel economy. Examples of prior art electric cars, hybrid electric passenger cars, hybrid electric SUVs and hybrid electric crossovers are 2001-2007 Toyota Prius, 2005-2007 Toyota Highlander hybrid, 2007 Ford Escape Hybrid, 2008 Chevy Tahoe “Two-mode” Hybrid, 2008 GMC Yukon, 1997 General Motors EV1, AC Propulsion eBox and T-zero.
Some light trucks are outfitted with mechanical four-wheel-drive (4WD) or all-wheel-drive (AWD) transmissions and differentials to improve handling when driving in slippery road conditions. Examples are 2007 Audi Q7, 2007 Volkswagen Touareg and 2007 Toyota 4-Runner. These additional drive components adds significant amount of weight to the vehicles. Operating and maintaining a light truck is generally more expensive compared to smaller passenger vehicles due to higher fuel consumption and wear and tear on drivetrain parts because of the added weight. As a matter of fact, most of the off-road-capable vehicles sold in the United States are never taken off-road and yet they carry the extra weights of the heavy duty components, which severely impact their fuel efficiency compared to other lighter vehicle types of the same size. Therefore, it would be advantageous to incorporate a four-wheel-drive response without the transmission or differential parts.
Not realizing the benefits of the modularity and flexibility that an electric coupling can offer, many inventors resort to mechanical solutions in which the power sources and the drive wheels are joined by mechanical couplings, or incremental improvements on the transmission parts. Such designs are described in U.S. Pat. Nos. 5,558,589, 5,931,757, 6,090,005 for A TWO-MODE, COMPOUND-SPLIT, HYBRID TRANSMISSION, 6,360,834 for a HYBRID ELECTRIC VEHICLE, 6,579,201 for an ELECTRIC HYBRID FOUR-WHEEL DRIVE VEHICLE, 5,343,970 for a HYBRID ELECTRIC VEHICLE, 7,237,634 for HYBRID VEHICLES, 6,840,341 for PARALLEL HYBRID VEHICLE, 6,945,345 for HYBRID ELECTRIC VEHICLE HAVING ALTERNATE POWER SOURCES, 6,656,083 for a HYBRID DRIVE SYSTEM, 6,811,508 for a HYBRID TRANSMISSION, PARTICULARLY FOR MOTOR VEHICLES, 6,852,053 for a DRIVETRAIN FOR A VEHICLE, 7,261,661 for a PARALLEL HYBRID TRANSMISSION HAVING A SINGLE MOTOR/GENERATOR, 7,220,199 for an INFINITELY VARIABLE POWER BRANCHING TRANSMISSION WITH TWO OPERATING MODES, 7,210,546 for a CONTROLLER AND CONTROL METHOD FOR A HYBRID ELECTRIC VEHICLE POWERTRAIN, 7,017,693 for a DRIVE DEVICE FOR HYBRID VEHICLE and 6,936,991 for METHOD AND APPARATUS FOR MOTOR CONTROL.
Prior arts hybrid electric vehicles are typically smaller in size, mechanically complex and expensive to buy and maintain. They sometimes even the fuel savings of the entire lifetime of the vehicle cannot justify for the extra costs. Prior art electric vehicles, similar to the one described in U.S. Pat. No. 5,212,431 for ELETRIC VEHICLE, produce no emission on board but typically have limited passenger and cargo capacity or operational radius. The process of generating electricity on the power grid involves burning fossil fuel and, based on the current energy mix, the emission could be higher than some other alternative methods of generating electricity onboard. Due to the limitation in current battery technologies, electric vehicles are typically small, underpowered, expensive, and thus, according to General Motors Corporation, impractical to be deployed in a large scale. Prior art hybrid electric vehicles, conventional passenger cars and conventional light trucks alike lack the ability to adapt to other fuel sources. This creates a barrier to entry for alternative fuel businesses because the cost to retrofit a vehicle to use another fuel source is generally cost-prohibitive. Therefore, a solution that offers the owner of the vehicle the liberty to choose between multiple fuel sources is highly desirable.
Another problem is that while many consumers prefer larger vehicles because of the perceived safety of these larger vehicles, the reality is that most light trucks are built using existing commercial truck platforms. Higher centers of gravity and uneven weight distributions of a light truck also affect the vehicle's stability, which further increases the chance of a collision. Their body-over-frame designs also lack the sophisticated “crumble zones” commonly found in smaller passenger vehicles and make the occupants more susceptible to injuries during a crash. A modular design allows the designer to free up the space in front of the vehicle for more freedom in crumble zone design. Therefore, a solution that employs modular components, which allows designers to relocate components to meet the desired weight distribution and as a prerequisite to create improved crumble zone structures, is highly desirable.
It is therefore an object of the invention to improve energy efficiency compared to a similar prior art in the same vehicle class, which is typically measured by the amount of energy consumed over the distance traveled.
It is another object of the invention to meet the performance, safety and payload capacities of a similar prior art in the same vehicle class.
It is another object of the invention to provide an all-wheel-drive propulsion system to improve traction.
It is another object of the invention to reduce operational and maintenance costs compared to a similar prior art in the same vehicle class.
It is another object of the invention to sustain a longer service life compared to a similar prior art in the same vehicle class.
It is another object of the invention to operate on more than one energy source to increase demand for alternative energy sources.
It is another object of the invention to provide an electric propulsion system that is capable to operate entirely on electricity.
It is another object of the invention to enable economical aftermarket exchanges of onboard power plants.